Method of film formation and method for manufacturing semiconductor device

ABSTRACT

This invention relates to a method of film formation in which, when a silicon oxide film (a NSG film: a Non-doped Silicate Glass) is formed on a substrate having a recess by a CVD method using a mixed gas containing a TEOS and ozone, a surface dependency of the substrate is deleted to embed a silicon oxide film into the recess of the surface thereof. The invention comprises a process forming a phosphorus containing insulating film  14  as a base layer on the surface of a substrate  11  and a process forming a silicon-containing insulating film  15  on the phosphosilicate glass film  14  by the chemical vapor deposition method used a mixed gas containing a ozone-containing gas and a silicon-containing gas.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a method of film formation and a methodfor manufacturing a semiconductor device in which, when a silicon oxidefilm (a NSG film: a Non-doped Silicate Glass) is formed on a substratehaving a recess by a CVD method using a mixed gas containing a TEOS andozone, a surface dependency of the substrate is deleted to embed asilicon oxide film into the recess of the surface thereof.

[0003] The surface dependency is defined as a property such that a filmformation depends on a property of a surface on which a film isdeposited.

[0004] 2. Description of the Prior Art

[0005] In recent years, micronizing has been advanced in thesemiconductor device. The recess narrow in width and deeper in depthsuch as the recess between wirings and the recess in which an insulatingmaterial is embedded for an insulating element separation is designed tobe formed on a semiconductor substrate surface. In such semiconductordevice, an insulating film is required to be embedded in the recess.

[0006] Therefore, the silicon oxide film excellent in film quality(hereinafter referred to as a High O₃/TEOS SiO₂ film) is required to beformed and to be embedded in the recess without clearance. A CVD methodis used as a method of the film formation. Mixed gas containing both theTEOS (Tetraethylorthosilicate) and the ozone-containing gas containinghigh concentration O₃ is used as a deposition gas, said ozone-containinggas containing O₃ of 1% or more in O₂.

[0007] However, since the High O₃/TEOS SiO₂ film is sensitive to aproperty of the surface of the substrate, a property of a depositingfilm tends to be influenced. An influence of the surface dependencyappears as reduction of a film formation rate, surface roughness of thedepositing film and reduction of film quality. Therefore, in order todeposit the High O₃/TEOS SiO₂ film having the same film formation rate,surface condition of the depositing film and the film quality of thedepositing film where the film on a silicon substrate is deposited, itis required for the surface of the substrate to design the filmformation of the High O₃/TEOS SiO₂ film to be not influenced by thesurface dependency. Heretofore, in order to delete such surfacedependency, the following countermeasures are given:

[0008] {circle over (1)} The silicon oxide film is formed as a baselayer on the surface of the substrate by a plasma enhanced CVD. This isdisclosed in Japanese Laid-open Patent Publication No.Hei.7-211712.

[0009] {circle over (2)} The surface of the substrate is exposed toplasma gases. This is disclosed in Japanese Laid-open Patent PublicationNo.Hei.4-94539.

[0010] {circle over (3)} The silicon oxide film hereinafter referred toas a Low O₃/TEOS SiO₂ film) is formed as a base layer on the surface ofthe substrate by the CVD method. As the film formation gas, the reactiongas containing the ozone-containing gas containing low concentration O₃whose the concentration of O₃ in O₂ is less than 1% and the TEOS isused. This is disclosed in Japanese Laid-open Patent PublicationNo.Hei.3-198340. Furthermore, the following method that the methodsdescribed above are combined is used.

[0011] {circle over (4)} The Low O₃/TEOS SiO₂ film is formed as the baselayer on the surface of the substrate by the CVD method andsubsequently, the Low O₃/TEOS SiO₂ film is exposed to plasma gases. Areaction gas containing both the TEOS and a low ozone-containing gassuch that the concentration of O₃ in O₂ is as low as less than 1% isused as the film formation gas of the Low O₃/TEOS SiO₂ film.

[0012] {circle over (5)} The High O₃/TEOS SiO₂ film is formed as thebase layer on the surface of the substrate by the CVD method andsubsequently, the High O₃/TEOS SiO₂ film is exposed to plasma gases. Areaction gas containing both the TEOS and a high ozone-containing gassuch that the concentration of O₃ in O₂ is as high as not less than 1%is used as the film formation gas of the High O₃/TEOS SiO₂ film.

[0013] In addition, the methods for delating the surface dependency ofthe substrate are disclosed in Japanese Laid-open Patent PublicationNo.Hei.7-66131 or the like.

[0014] By such method, the O₃/TEOS SiO₂ film of which the depositingfilm does not depend upon the surface dependency of the substrate andwhich has the sufficient fluid ability can be formed.

PROBLEMS TO BE SOLVED BY THE INVENTION

[0015] However, in the methods for deleting the surface dependencydescribed above, there are the following problems:

[0016] That is, in the method forming the silicon oxide film as the baselayer on the surface of the substrate by the CVD method described in theitem {circle over (1)},

[0017] since the silicon oxide film by the plasma enhanced CVD method ispoorly good in step coverage, it is not suitable for embedding therecess narrow in width and deeper in depth.

[0018] Moreover, in the method of the item {circle over (2)} exposingthe surface of the substrate to plasma gases, since a plasma apparatusis required, the apparatus becomes extensive. Moreover, in such method,there are problems that an increase in cost is led and it is a questionwhether reform can be performed up to the bottom of the recess narrow inwidth and deeper in depth or not by the plasma.

[0019] Furthermore, in the method of the item {circle over (3)}, athickness of the Low O₃/TEOS SiO₂ film is required at least 50 nm ormore. It is not suitable for embedding to the recess narrow in width anddeeper in depth.

[0020] Moreover, with regard to the item {circle over (4)} and the item{circle over (5)} also, there are the same problems as the item {circleover (2)} and the item {circle over (3)}.

SUMMARY OF THE INVENTION

[0021] It is the object of this invention to provide a method of filmformation and a method for manufacturing a semiconductor device capableof securely deleting the surface dependency of the substrate to form aninsulating film being excellent in film quality.

[0022] The object of this invention is to provide a method of filmformation and a method for manufacturing a semiconductor device capableof embedding the insulating film without clearance in a recess of thesubstrate having the recess narrow in width and deeper in depth.

[0023] As described above, in this invention, a phosphorus-containinginsulating film such as a phosphosilicate glass film is formed as a baselayer on the surface of the substrate. Furthermore, on thephosphorus-containing insulating film, a silicon-containing insulatingfilm is formed by a chemical vapor film formation using the mixed gascontaining the ozone-containing gas and a silicon-containing gas.

[0024] According to experiments by the inventor of the applicationconcerned, in the case of depositing the silicon-containing insulatingfilm by a chemical vapor deposition method using the mixed gascontaining the ozone containing gas and a silicon-containing gas on thesubstrate, the surface dependency of the substrate can be deleted bysheathing the surface of the substrate with the phosphorus-containinginsulating film such as a phosphosilicate glass film (a PSG film) or aborophosphosilicate glass film (BPSG film).

[0025] Incidentally, it has been stated that, when the High O₃/TEOS SiO₂film is formed by the chemical vapor deposition method using theozone-containing gas and a silicon-containing gas containing highconcentration ozone (defined as the concentration of ozone in oxygen is1% or more), the surface dependency to the deposition film on thesubstrate appears remarkably. According to the invention, since thesurface dependency can be deleted by sheathing the surface of thesubstrate with the phosphorus containing insulating film, the sufficientfluid ability can be obtained, even when the High O₃/TEOS SiO₂ filmbeing ready to be influenced by the surface dependency is deposited.

[0026] Moreover, the surface dependency can be deleted sufficiently byphosphorus-containing insulating film with a thin film thickness ofapproximate 10 nm in film thickness. Therefore, even the inside of therecess narrow of, at least, approximate 20 nm or more in width can besheathed. Moreover, the upper limit of the film thickness ofphosphorus-containing insulating film is influenced by the width of therecess. At this point of time, the film thickness of thephosphorus-containing insulating film is defined preferably such thatthe film thickness of the phosphorus-containing insulating film becomesthin sufficiently as compared with the silicon-containing insulatingfilm in the entire film thickness of an interlayer dielectric filmconstituted by the phosphorus containing insulating film as the baselayer and the silicon containing insulating film which lies thereon.Usually, it can be acceptable sufficiently when being formed withinapproximate 100 nm.

[0027] Therefore, when there is the recess narrow in width and deeper indepth on the surface of the substrate, recess can be embedded with thesilicon oxide film without clearance, without generating voids and seamson the silicon oxide film formed in recess.

[0028] In this case, the ozone-containing gas, the silicon-containinggas and the phosphorus-containing gas are discharged by a first gasdischarge means to form the phosphorus-containing insulating film andthen the ozone-containing gas and the silicon-containing gas aredischarged by a second gas discharge means continuously after ceasingthe discharge by the first discharge means to form the silicon oxidefilm. Incidentally, it has been found by the experiments that in orderto delete the surface dependency of the surface of thephosphorus-containing insulating film, when subsequently forming thesilicon-containing insulating film on the phosphorus-containinginsulating film, it is required to perform such that nophosphorus-containing gas is contained in the reaction gas. That is,when the silicon-containing insulating film is formed using a gasdischarge means which differs from the gas discharge means where formingthe phosphorus-containing insulating film, the surface dependency at thesurface of the phosphorus-containing insulating film can be deleted. Adeposition chamber for the phosphorus-containing insulating film may beswapped with a deposition chamber for the silicon-containing insulatingfilm or the alternate gas discharge means may be switched respectivelyupon forming also.

[0029] Moreover, the following fact has been verified by theexperiments. After the process forming the phosphorus-containinginsulating film and before the process forming the silicon-containinginsulating film on the phosphorus-containing insulating film, thesurface of the phosphorus-containing insulating film is exposed to theatmosphere, or the surface of the phosphorus-containing insulating filmis exposed to water vapor while heating the surface of thephosphorus-containing insulating film. Therefore, the surface of thephosphorus-containing insulating film is converted to hydrophobicity,and when the surface of the phosphorus-containing insulating film isconverted to hydrophobicity, the surface dependency in thementioned-above depositing film can be suppressed. Especially, when theHigh O₃/TEOS SiO₂ film being ready to be influenced by the surfacedependency is deposited, such treatment is performed preferably.

[0030] Furthermore, the ozone-containing gas used in the film formationof the silicon-containing insulating film is the gas containing ozone ofthe concentration of less than 10% in oxygen.

[0031] As described above, to use the phosphorus-containing insulatingfilm as the base layer is effective, in particular, when depositing theHigh O₃/TEOS SiO₂ film being ready to be influenced by the surfacedependency using the high ozone-containing gas such that theconcentration of ozone in oxygen is as high as 1% or more.

[0032] As a matter of course, this is effective also when depositing thesilicon oxide film (the Low O₃/TEOS SiO₂ film) being not ready to beinfluenced by the surface dependency using the low ozone containing gassuch that the concentration of ozone in oxygen is as low as less than1%.

[0033] The reason why is that according to this deposition, penetrationof moisture and migration of alkali ions from the Low O₃/TEOS SiO₂ filmto the substrate can be prevented.

[0034] In the case of depositing the silicon-containing insulating filmby CVD method using the mixed gas of the O₃/TEOS, the flowability of thedepositing film can be increased by regulating the depositiontemperature within the range of 350° C. to 550° C. In thedescribed-above deposition temperature, in order to obtain theparticularly sufficient flowability of the depositing film, it ispreferable that the deposition temperature is regulated within the rangeof 375° C. to 425° C.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1A to FIG. 1C are flowcharts of a method of film formationand a method for manufacturing a semiconductor device according toembodiments of the invention.

[0036]FIG. 2A and FIG. 2B are photography showing cross-section shapesof a silicon-containing insulating film formed on a substrate with astep and a groove by the method of film formation and the method formanufacturing the semiconductor device according to embodiments of theinvention.

[0037]FIG. 3A is a sectional view showing a substrate with a step usedin the method of film formation and the method for manufacturing thesemiconductor device according to embodiments of the invention.

[0038]FIG. 3B is a sectional view showing a substrate with a trenchgroove used in the method of film formation and the method formanufacturing the semiconductor device according to embodiments of theinvention.

[0039]FIG. 4 is a view showing the correlation between the surfacedependency of a deposition rate and an angle of contact of the O₃/TEOSNSG film being formed by the method of film formation according toembodiments of the invention.

[0040]FIG. 5 is a graph obtained by investigating, by showing types ofthe base layers as a parameter, the correlation between the ratio of thedeposition rates and an ozone concentration of the O₃/TEOS NSG filmbeing formed by the method of film formation according to embodiments ofthe invention.

[0041]FIG. 6 is a side view showing a constitution of a depositionchamber applied to the method of film formation according to embodimentsof the invention.

[0042]FIG. 7 is a sectional view showing cross-section shape of asilicon-containing insulating film formed on a substrate with the stepand the groove by the method of film formation according to a comparisonexample.

DESCRIPTION OF THE PREFRRED EMBODIMENTS

[0043] Hereafter, the embodiments of the invention are describedreferring to the drawings.

[0044] (1) Basic Data of this Invention

[0045] This invention is based on knowledge in the depositing reactionof the O₃/TEOS SiO₂ film in the case using a chemical vapor depositionmethod (a CVD method) as described below items (i) to (iv).

[0046] (i) The flowability during depositing the O₃/TEOS SiO₂ filmappears at the deposition temperature within the range of 375° C. to425° C.

[0047] On the other hand, when the deposition temperature exceeds 450°C., isotropic growth is shown. At temperature exceeding 500° C., thedeposition of the silicon-containing insulating film by the CVD methodused the mixed gas of O₃+TEOS (hereinafter represented as an O₃/TEOS)becomes the perfectly isotropic deposition.

[0048] In this case, the silicon-containing insulating film 4 is alsocapable of being formed in a narrow and deep recess 3 as shown in FIG.7. However, a void 5 or slit 6 may occur if a thickness of thesilicon-containing insulating film 4 is thicker.

[0049] (ii) FIG. 4 is a view showing the relationship among a propertyof the surface whether the base layer surface is hydrophilic orhydrophobic, an angle of contact (θ) of water deposited on a base layersurface and the ratio of the deposition rates of various films beingformed on the base layer.

[0050] As shown in FIG. 4, where an angle of contact (θ) refers to theangle which the tangent to the drop of water at the contact surface withthe base layer surface forms with the base layer surface, when waterdeposited on a base layer surface is flocculated to make a drop of waterby surface tension. A ratio of the deposition rates refers to the ratioof the deposition rate where the same film is film-deposited on variousbase layers with respect to the deposition rate where various films areformed on silicon surface directly. It is shown that as the ratio of thefilm deposition rates approaches 1, the surface dependency is moresuppressed.

[0051] Moreover, the term “Th.SiO₂” in FIG. 4 refers to the siliconoxide film formed by thermal oxidation. The term “AD” refers to “asdeposited”, that is, the meaning of “immediately after deposition”. Theterm “EX” refers to “after exposure”, that is, the meaning of “afterexposing to the atmosphere”.

[0052] In the comparison data of the ratio of the deposition rates, thehigh ozone-containing gas that the concentration of ozone in oxygen is5% is used as an oxidizing gas used in the film formation of aphosphosilicate glass (PSG)(AD), an impurity-free silicon oxide film(NSG), a borophosphosilicate glass film (BPSG) and PSG (EX) in variousfilms.

[0053] As shown in FIG. 4, the surface dependency of the O₃/TEOS SiO₂film to the base layer is influenced depending upon the angle of contact(θ) of water deposited on the base layer surface, that is, whether beinghydrophilic or hydrophobic.

[0054] That is, when the surface of the base layer is hydrophilic, thesurface dependency of the depositing film is high, and when the surfaceof the base layer is hydrophobic, the surface dependency of thedepositing film is low. Moreover, in FIG. 4, the reason why even thoughthe NSG is hydrophilic, the surface dependency of the depositing film tothe base layer is low is unknown with the current state of the art.

[0055] (iii) FIG. 5 is a graph showing the relationship between theozone concentration in the ozone-containing gas used in film formationof the NSG film deposited on the base layer and the ratio of thedeposition rates of the NSG film. The various films as the base layersare shown as a parameter.

[0056] The ratio of the deposition rates expressed in a linear scale isshown on the vertical axis the horizontal axis. The concentration ofozone (%) in oxygen expressed in a linear scale is shown on thehorizontal axis.

[0057] Moreover, in the indication of the various films as the baselayers, the indication of “NSG 4% AD” shows that it is the NSG filmformed using the ozone-containing gas that the concentration of ozone isless than 4%. In addition, it shows that immediately after deposition,deposition is performed thereon.

[0058] The indication of “PSG 2 mol % EX” shows that it is the PSG filmcontaining phosphorus of 2 mol % and after exposing to the atmosphere,deposition is performed thereon.

[0059] The indication of “PSG 4 to 6 mol % EX” refers to the PSG filmcontaining phosphorus of 4 to 6 mol %.

[0060] The indication of “BPSG 8 to 8 mol % AD” shows that it is theBPSG film containing boron of 8 mol % and phosphorus of 8 mol % andimmediately after deposition, deposition is performed thereon.

[0061] Other indications conform to the described-above indications.Moreover, the concentration of ozone in the ozone-containing gas used indeposition of the PSG film and the BPSG film is both defined as 4%.

[0062] As shown in FIG. 5, there is the significant correlation betweenthe concentration of ozone in the ozone-containing gas used indeposition of the silicon-containing insulating film and the surfacedependency.

[0063] Moreover, in the case that the base layer is the PSG, immediatelyafter deposition of the base layer (AD), the surface dependency in thebase layer is high. However, it is understood that when the base layeris exposed to the atmosphere (EX), the surface of the base layer isconverted from hydrophilic to hydrophobic, whereby the surfacedependency of the depositing film become low.

[0064] Next, the degree of the surface dependency according to the typeof the base layer is shown in Table 1. TABLE 1 Surface dependency Typedepositing film Type of base layer High High O₃ NSG film Th.SiO₂ (DR <0.7) HD PSG (AD) SOG Low High O₃ NSG film BSG, PSG (EX) (0.7 < RD < 1.0)BSG film BPSG, P—SiO SiN No dependence High O₃ NSG film P—SiO, Al,refractory metal polysilicon, silicon PSG film, BPSG film Every type ofclean Low O₃ NSG film substrate

[0065] Table 1 is the table comparing the degrees of the surfacedependencies where the Low O₃ NSG film (referred to the Low O₃/TEOS SiO₂film) base layer, the High O₃ NSG film (refer to the High O₃/TEOS SiO₂film), the BSG film, the PSG film or the BPSG film are formed on thevarious films as the base layer.

[0066] According to Table 1, the High O₃ NSG film is influenced stronglyby the surface dependency of the base layer when being deposited on aTh. SiO₂, HDPSG (AD) (refer to a high concentrationphosphorus-containing PSG film (AD)) or a SOG (Spin-On-Glass) as thebase layer. That is, the ratio of the deposition rates (DR) becomes lessthan 0.7.

[0067] On the other hand, the influence by the surface dependency of thebase layer is an intermediate degree, when the High O₃ NSG film isdeposited on BPSG, BSG, PSG (EX), or P-SiO film as the base layer. Thatis, the ratio of the deposition rates (DR) becomes 0.7 or more and lessthan 1.

[0068] Moreover, in the case of depositing a P—SiO, it is not influencedperfectly by the surface dependency under that P—SiO film. Furthermore,even when on any type of surface, the PSG film and the BPSG filmbeginning with the Low O₃ NSG film are deposited, these films are notinfluenced perfectly by the surface dependency under the PSG film andthe BPSG film.

[0069] Moreover, a P—SiO film is the silicon oxide film deposited usingplasma of a gas containing the TEOS. Moreover, a “SiN film” representsthe silicon nitride film.

[0070] Other films can be interpreted in conformance with thedescribed-above description.

[0071] (iv) When the O₃/TEOS SiO₂ film is deposited on the base layer, aso-called barrier layer or a shield layer is required between the baselayer and the O₃/TEOS SiO₂ film. The barrier layer or the shield layeris required for insulating the O₃/TEOS SiO₂ film and the base layersurface, for preventing moisture from transmitting and for deleting thesurface dependency of the depositing film in the base layer or the like.Moreover, the base layer surface being exposed to some types ofmaterials is required to be uniformed.

[0072] This invention is devised based on the knowledge described above,and hereinafter, embodiments of the invention are described.

[0073] (2) Embodiments of the Invention

[0074]FIG. 1A to FIG. 1C are sectional views illustrating theembodiments of the invention. FIG. 6 is a side view showing aconstitution of the deposition chamber.

[0075] First, a substrate 11 shown in FIG. 1A is placed on a placingtable 104 in a deposition chamber 101. On the surface of the substrate11, asperties are caused by a step (a recess) 12 and a groove (a recess)13. For example, as shown in FIGS. 3A and 3B, such asperties are theasperties being caused by a trench groove 22 formed on a surface of asemiconductor substrate 21 and wiring 24 a and 24 b formed on a baseinsulating layer 23.

[0076] Subsequently, the substrate 11 is heated to be kept within thetemperature of 350° C. to 550° C. The temperature is kept preferablywithin 375° C. to 425° C. In this embodiment, for example, it is definedas 400° C.

[0077] Next, as shown in FIG. 1B, a phosphosilicate glass film (aphosphorus-containing insulating film) 14 thin in thickness is depositedon the surface of the substrate 11 as the base layer by the CVD method.For this purpose, a gas conduit 112 a reaching a gas discharge means 103is closed and gas conduits 112 b-115-111 a, and 111 b-111 a arecommunicated by valve 105, 106. With this, a reaction gas 121 consistingof the ozone-containing gas that the concentration of ozone in oxygen is5% and a nitrogen gas containing the TEOS (a silicon-containing gas) andTMOP (Trimetylphosphate (PO(OCH₃)₃): a phosphorus-containing gas) areintroduced to a first gas discharge means 102 on the substrate 11. Theozone-containing gas is supplied through an O₂ source 104 and ozonizer110, a nitrogen gas containing the TEOS is supplied through TEOS source108, and TMOP is supplied through TMOP source 107.

[0078] The reaction gas reacts by the temperature of the substrate 11being increased by heating to deposit a phosphor glass film 14 on thesubstrate 11.

[0079] At this point of time, the flow rate of the TMOP is adjusted inadvance such that a phosphorus content in the phosphosilicate glass film14 becomes less than 10%.

[0080] Moreover, the film thickness of the phosphosilicate glass film 14is determined such that the film thickness becomes the sufficientthickness required to delete the surface dependency and in considerationof a width and a depth of the step (the recess) 12 and the groove (therecess) 13. That is, the sufficient thickness required to delete thesurface dependency has been found to be approximate 10 nm or more by theexperiments.

[0081] Moreover, the film thickness of the phosphosilicate glass film 14is influenced by the width of (the recess), whereby it is preferable tobe formed as thin as possible such that the groove (the recess) 13 isnot filled with only the phosphosilicate glass film 14. In general, inthe entire film thickness of the interlayer dielectric film constitutedby the phosphosilicate glass film 14 as the base layer and a siliconoxide film 15 laying thereon, the film thickness of the phosphosilicateglass film 14 is preferably established so that the film thickness ofthe phosphosilicate glass film 14 becomes sufficiently thin as comparedwith the film thickness of the silicon oxide film 15. Usually, when thefilm thickness of the phosphosilicate glass film 14 is approximate 100nm, it can be recognized to be sufficiently thin. In this embodiment,for example, a deposition time is established such that the filmthickness of the phosphosilicate glass film 14 becomes 10 nm or more andless than 100 nm.

[0082] After a lapse of the deposition time established by the abovedescription, the phosphosilicate glass film 14 within the range of 10 to100 nm in thickness is formed on the substrate 11. Since the depositiontemperature of the phosphosilicate glass film 14 is within the range of375° C. to 425° C., the phosphosilicate glass film 14 is smooth andgrows in an approximately isotropic condition regardless the type ofmaterial exposed to the substrate 11. Moreover, the surface dependencyof the depositing film is deleted by the phosphosilicate glass film 14.

[0083] Moreover, it is effective to perform the treatment exposing towater vapor under the condition of heating at the same temperature asthe deposition temperature in the deposition chamber, before forming thesilicon oxide film (the silicon-containing insulating film) on thephosphosilicate glass film 14. Therefore, the surface on thephosphosilicate glass film 14 is converted from hydrophilic tohydrophobic.

[0084] Subsequently, the TMOP is stopped and a gas supplying line isswitched to a different gas supplying line 112 b-111 a from the gassupplying lines 112 b-115-111 a and 111 b-111 a through which thereaction gas 121 containing the TMOP flew. Therefore, the ozonecontaining gas containing the same concentration ozone where thephosphosilicate glass film 14 is deposited and the TEOS (asilicon-containing gas) continuously flow into the same depositionchamber 101 through the second gas discharge means 103 on the substrate11. Moreover, the temperature of the substrate also is kept as it is.That is, the temperature of the substrate is kept within the temperatureof 350° C. to 550° C., preferably within 375° C. to 425° C. in commonwith the deposition temperature of the phosphosilicate glass film.

[0085] As shown in FIG. 1C, while keeping this condition, thesilicon-containing insulating film (the High O₃/TEOS SiO₂ film: thesilicon-containing insulating film) 15 is formed on the phosphosilicateglass film 14. At this point of time, since the surface dependency ofthe depositing film in the base layer has been deleted, the High O₃/TEOSSiO₂ film 15 being deposited exhibits the significant flowability andflows into the recess 13 narrow in width.

[0086]FIG. 2A and FIG. 2B are photography showing cross-section of theHigh O₃/TEOS SiO₂ film 15 formed in the recess 12 wide in width and 13narrow in width on the substrate 11. The striped patterns observed inthe High O₃/TEOS SiO₂ film 15 in the photography are caused by forming adifferent layer at each deposition of the High O₃/TEOS SiO₂ film 15 withthe predetermined film thickness in order to facilitate to observe howthe depositing film deposits.

[0087] As shown in FIG. 2A, at the recess 12 wide in width, formation ofa flowing shape is recognized and moreover, as shown in FIG. 2B, at therecess 13 narrow in width, generation of the voids and the seams in theHigh O₃/TEOS SiO₂ film 15 of the recess 13 can be suppressed to embedthe High O₃/TEOS SiO₂ film 15 into the recess 13 without clearance.

[0088] As described above, according to the embodiments of the inventionsince the surface dependency of the depositing film can be deleted bysheathing the surface of the substrate 11 with the phosphosilicate glassfilm 14, the sufficient fluid ability can be obtained, even when theHigh O₃/TEOS SiO₂ film 15 being ready to be influenced by the surfacedependency is deposited.

[0089] Since the surface dependency of the depositing film can bedeleted sufficiently by the phosphosilicate glass film 14 with the thinfilm thickness, even the inside of the recess narrow in width can besheathed sufficiently.

[0090] Therefore, when there is the recess 13 narrow in width on thesurface of the substrate 11, the High O₃/TEOS SiO₂ film 15 can beembedded into the recess 13 without clearance, without generating thevoids and the seams on the High O₃/TEOS SiO₂ film 15 in the recess 13.

[0091] Furthermore, since the deposition temperature at forming the HighO₃/TEOS SiO₂ film 15 is regulated within the range of 350° C. to 550°C., preferably within the range of 375° C. to 425° C., on the occasionof depositing the High O₃/TEOS SiO₂ film 15 by the CVD method using themixed gas of the O₃/TEOS, the flowability of the depositing film can beincreased.

[0092] Moreover, in the embodiments of the invention described above,although the PSG film is used as the base layer 14, the BPSG film may beused as a substitute of the PSG film.

[0093] As the ozone-containing gas used in deposition of thesilicon-containing insulating film 15 on the base layer 14, the HighO₃/TEOS SiO₂ film is formed using the gas containing the highconcentration ozone such that the concentration of ozone in oxygen is ashigh as 1% or more and less than 10%. However, it can be applied also inthe case of depositing the silicon oxide film (the Low O₃/TEOS SiO₂film) being not ready to be influenced by the surface dependency usingthe ozone containing gas containing the low concentration ozone suchthat the concentration of ozone in oxygen is as low as less than 1%. Inthis case, by using the phosphorus-containing insulating film 14 such asthe phosphosilicate glass film, in particular, penetration of moistureand migration of alkali ions from the Low O₃/TEOS SiO₂ film to thesubstrate can be prevented except deleting of the surface dependency ofthe depositing film.

[0094] Furthermore, in the above description, after depositing thephosphosilicate glass film 14 and before forming the silicon oxide film15, the surface of the phosphosilicate glass film 14 is converted tohydrophobicity by exposing to water vapor. However, the gas dischargemeans used at forming the phosphosilicate glass film 14 may be swappedwith an alternate gas discharge means which is perfectly free from thedeposition of phosphorus. Whether this or that, the substrate 11 may bemoved out of the deposition chamber to expose to the atmosphere.Therefore, the surface dependency in the surface of the phosphosilicateglass film 14 can be deleted.

[0095] Moreover, in the above description, although the phosphosilicateglass film (the phosphor-containing insulating film) 14 is formed withinthe range of 10 to 100 nm in thickness, this is never limited thereto.Theoretically, it is essential only that the film thickness of thephosphorus-containing insulating film is less than one half of the widthof the recess. Accordingly, the upper limit of the film thickness of thephosphorus-containing insulating film would be influenced by the widthof the recess.

[0096] As described above, in the invention, the surface of thesubstrate is sheathed with the phosphorus-containing insulating filmsuch as the phosphosilicate glass film. Therefore, the surfacedependency of the depositing film can be deleted to the substrate toobtain the sufficient fluidity at depositing.

[0097] Moreover, the gas containing ozone of less than 10% in oxygen isused as the ozone-containing gas used in deposition of thesilicon-containing insulating film.

[0098] That is, it is applied to the High O₂/TEOS SiO₂ film which isdeposited using the high ozone-containing gas such that theconcentration of ozone in oxygen is 1% or more and which is ready to beinfluenced by the surface dependency, or the silicon oxide film (the LowO₃/TEOS SiO₂ film) which is deposited using the low ozone containing gasthat the concentration of ozone in oxygen is less than 1% and which isnot ready to be influenced by the surface dependency.

[0099] In the case of applying to the deposition of the High O₃/TEOSSiO₂ film, it is effective for deleting the surface dependency, and inthe case of applying to the deposition of the Low O₃/TEOS SiO₂ film, itis effective for preventing penetration of moisture and migration ofalkali ions from the Low O₃/TEOS SiO₂ film to the substrate rather thanfor deleting the surface dependency.

[0100] Moreover, since the surface dependency of the depositing film canbe deleted sufficiently by using the phosphorus-containing insulatingfilm such as the phosphosilicate glass film, even the inside of therecess narrow in width can be sheathed sufficiently.

[0101] Therefore, when there is the recess narrow in width on thesurface of the substrate, the recess 13 can be embedded with the siliconoxide film without clearance, without generating the voids and the seamson the silicon oxide film formed in the recess.

[0102] Furthermore, since the deposition temperature at forming thesilicon-containing insulating film is regulated within the range of 350°C. to 550° C., preferably within the range of 375° C. to 425° C., on theoccasion of depositing the silicon-containing insulating film by the CVDmethod using the mixed gas of the O₃/TEOS, the flowability of thedepositing film can be increased.

What is claimed is:
 1. A method of film formation comprising the stepsof: forming a phosphorus-containing insulating film on a surface of asubstrate as a base layer; and forming a silicon-containing insulatingfilm on said phosphorus-containing insulating film by a chemical vapordeposition using a mixed gas containing a ozone-containing gas and asilicon-containing gas.
 2. The method of film formation according toclaim 1 , wherein after a step of forming said phosphorus-containinginsulating film and before a step of forming the silicon-containinginsulating film on said phosphorus-containing insulating film, a surfaceof said phosphorus-containing insulating film is exposed to theatmosphere, or the surface of said phosphorus-containing insulating filmis exposed to water vapor while heating the surface of saidphosphorus-containing insulating film.
 3. The method of film formationaccording to claim 1 , wherein a film thickness of saidphosphorus-containing insulating film deposited is within the range of10 nm to 100 nm.
 4. The method of film formation according to claim 1 ,wherein said ozone-containing gas is a gas containing ozone of aconcentration of not more than 10% in oxygen.
 5. The method of filmformation according to claim 1 , wherein said silicon-containing gas isa gas containing tetraethylorthosilicate (TEOS).
 6. The method of filmformation according to claim 1 , wherein a deposition temperature duringforming said silicon-containing insulating film is within the range of350° C. to 550° C.
 7. The method of film formation according to claim 6, wherein the deposition temperature during forming saidsilicon-containing insulating film is within the range of 375° C. to425° C.
 8. The method of film formation according to claim 1 , whereinsaid phosphorus-containing insulating film is any one of aphosphosilicate glass film (a PSG film) and a borophosphosilicate glassfilm.
 9. The method of film formation according to claim 8 , wherein aphosphorus concentration in said phosphosilicate glass film is not morethan 10 mol %.
 10. A method of film formation comprising the steps of:discharging a ozone-containing gas, a silicon-containing gas and aphosphorus-containing gas by a first gas discharge means to form aphosphorus-containing insulating film on a surface of a substrate as abase layer by a chemical vapor deposition; and discharging theozone-containing gas and the silicon-containing gas by a second gasdischarge means which differs from said first gas discharge meanscontinuously after ceasing the discharge by the first gas dischargemeans to form a silicon-containing insulating film on saidphosphorous-containing insulating film by the chemical vapor deposition.11. The method of film formation according to claim 10 , wherein after astep of forming said phosphorus-containing insulating film and before astep of forming the silicon-containing insulating film on saidphosphorus-containing insulating film, a surface of saidphosphorus-containing insulating film is exposed to the atmosphere, orthe surface of said phosphorus-containing insulating film is exposed towater vapor while heating the surface of said phosphorus-containinginsulating film.
 12. The method of film formation according to claim 10, wherein a film thickness of said phosphorus-containing insulating filmdeposited is within the range of 10 nm to 100 nm.
 13. The method of filmformation according to claim 10 , wherein said ozone-containing gas is agas containing ozone of a concentration of not more than 10% in oxygen.14. The method of film formation according to claim 10 , wherein saidsilicon-containing gas is a gas containing tetraethylorthosilicate(TEOS).
 15. The method of film formation according to claim 10 , whereina deposition temperature during forming said silicon-containinginsulating film is within the range of 350° C. to 550° C.
 16. The methodof film formation according to claim 15 , wherein the depositiontemperature during forming said silicon-containing insulating film iswithin the range of 375° C. to 425° C.
 17. The method of film formationaccording to claim 10 , wherein said phosphorus-containing insulatingfilm is any one of a phosphosilicate glass film (a PSG film) and aborophosphosilicate glass film.
 18. The method of film formationaccording to claim 17 , wherein a phosphorus concentration in saidphosphosilicate glass film is not more than 10 mol %.
 19. A method formanufacturing a semiconductor device comprising the steps of: formingthe phosphorus-containing insulating film for sheathing a recess as thebase layer on the surface of the substrate having said recess; andsubsequently forming a silicon-containing insulating film on saidphosphorus-containing insulating film by a chemical vapor depositionusing a mixed gas containing a ozone-containing gas and asilicon-containing gas, so that said recess is embedded with the siliconoxide film.
 20. A method of film formation comprising the steps of:discharging a ozone-containing gas, a silicon-containing gas and aphosphorus-containing gas by a first gas discharge means to form aphosphorus-containing insulating film for sheathing a recess on asurface of a substrate having said recess as a base layer by a chemicalvapor deposition; and discharging the ozone-containing gas and thesilicon-containing gas by a second gas discharge means which differsfrom said first gas discharge means continuously after ceasing thedischarge by the first gas discharge means to form a silicon-containinginsulating film on said phosphorous-containing insulating film by thechemical vapor deposition, so that said recess is embedded with thesilicon oxide film.